Field of Invention
Various exemplary embodiments of the present invention relate generally to an electronic device, and more particularly, to a semiconductor memory device and a method of operating the same.
Description of Related Art
With the surge in usage of mobile information devices using semiconductor memory devices as storage media, especially smartphones and tablets, these semiconductor memory devices have gained increasing interest and importance. The emergence of a wide range of applications as well as a high-speed processor or multi-core parallelism has required increased performance and reliability of semiconductor memory devices.
A semiconductor memory device is a storage device that is realized using a semiconductor made from, for example, silicon (Si), germanium (Ge), gallium arsenide (GaAs), or indium phosphide (InP). Semiconductor memory devices can be classified as volatile memory devices or nonvolatile memory devices. A volatile memory device is unable to retain stored data when the power is turned off. Volatile memory devices include static random access memory (SRAM) device, dynamic RAM (DRAM) device, synchronous DRAM (SDRAM) device, or the like. A non-volatile memory device can retain stored data even when powered off. Non-volatile memory devices may include read only memory (ROM) device, programmable ROM (PROM) device, electrically programmable ROM (EPROM) device, electrically erasable and programmable ROM (EEPROM) device, flash memory device, phase-change RAM (PRAM) device, magnetic RAM (MRAM) device, resistive RAM (RRAM) device, ferroelectric RAM (FRAM) device, or the like. A flash memory device may be classified as a NOR type or a NAND type.
A non-volatile memory device may include a plurality of memory blocks. Defective blocks among the plurality of memory blocks may be generated due to errors in the manufacturing process. A non-volatile memory device having a predetermined number or less defective blocks may be treated as normal.
However, specific memory blocks that may store security data, memory device ID information for example, should not be defective. Non-volatile memory devices having defects in specific memory blocks may be treated as failed regardless of the total number of defective blocks. This may result in reduced production yield of non-volatile memory devices.